Ullmann reaction



United States Patent 2,907,799 ULIJMANN REACTION Lawrence J. Hughes, University City, M0,, and Leo J. Weaver, Wakefield, Mass, assignors to Monsanto Chemical Company, St. Louis, Mo., a corporation of Delaware 7 No Drawing. Application May 31, 1955 Serial No. 512,322

' 14 Claims. (Cl. 260-668) halides-may be the same or dilferent, although the usual operation takes place between two molecules of the same compound. The following reactions are typical 'of the Ullmann procedure; a 1

. 'Although it will be apparent that the compositions involving the inter-reaction of two different aromatic halides are possible, because of the problem of separating the several products, these reactions are of lesser imporreactant, the metal particles are reacted only on the surface. and the'non-reactive surface ofcopper oxide or halide prevents further reaction. In the normal operalion of theUllmann process there is usually an inception period before the reaction is initiated, the reagents requiring a substantial period. of time under the reaction conditions before the first chemical reaction occurs.

In accordance with this novel procedure the Ullmann reactions are conducted in the presence of a mixture of the elemental copper or copper alloy and an aliphatic carboxylic acid having from to 24 carbon atoms. The precise mechanism of the reaction has not been definitely ascertained, however, in the presence. of the carboxylic acids there is no protective surface coating formed on the metal particles and as a result virtually all of the copper is consumed. The very large excess'which en- 1 Behenic acid tanc e. The halides which may be used in the practice of this invention are preferably chlorides, bromides or iodides, the fluorides being of lesser importance because of the rigorous conditions required to effect a practicable reaction. .The Ullmann process involves the mixing of the aromatic halide, or plurality of halides, with ele mental copper in finely divided state. Pure copper or a copper alloy, such as brass or bronze, may beused. In view of the fact that the copper enters the reaction to form at least what is believed to be a transitional metal organo compound, a stoichiometric proportion must be used. In the usual procedures several hundred per cent of the stoichiometric' requirements are charged to the reactor, because of the difliculty in subdividing the metal particles to a sufficient extent to utilize all of the copper. Al- "though the copper serves to remove the halogen from the produce a liquid reaction mixture.

cumbers the reaction and complicates the product separation, is not required. In the practice of the new procedure in the presence of carboxylic acids having from 10 to 24 carbon atoms, the reaction becomes almost immediate and the usual inception period is not required.

Suitable carboxylic acids for the practice of this invention are:

Stearic acid Arachidic acid Palmitic acid Myristic acid Linoleic acid Linolinic acid Carnaubic acid Laurie acid and analogous acids, both saturated and unsaturated, which have from 10 to 24 carbon atoms and mixtures of any of the above acids as derived by the saponification of animal or vegetable oils.

In the practice of the method: of this invention a stoichiometric proportion or at the most a slight excess of stoichiometric requirements of copper is 'used and Margaric acid from 0.1% to 10% of the stoichiometric equivalent of stearic acid is used which is intimately mixed with the coppenpreferably by milling or grindingwith the finely divided metal powder. The quantityof the aliphatic acids required 'in the practice of this invention will be sufficient to substantially utilize the copper metal butnot in quantity to prevent a free flowing suspension of the metal powder in the reaction medium.

A novel Ullmann process reactant is a copper or copper alloy in finely divided state which is intimately mixed with a fatty acid having from 10 to 24 carbon atoms. Preferred reactants of this type will have from 0.1 to 10% of the stoichiometric equivalent of the'copper in the metal powder. These reactants are preferably prepared by grinding the copper or copper alloy in the presence of-the required amount of the solid carboxylic acid.

In the usual practice of the Ullmann reaction, temperatures between and 400 C. are used, being sufficiently high to promote an active reaction and to insure the existence of afluid liquid reaction mixture, but not high enough to induce the decomposition of the reactants or product. In the preparation offhigh molecular weight aromatic compounds by the Ullmann process, it is frequently necmsary to introduce an inert solvent so as to dissolvethe high'molecular weight reactants and thereby Suitable organic solvents for this purpose are benzene,

I alkyl benzenes, aliphatic hydrocarbons and mixtures there- 3 utilizing .the novel elementalcopper reactants are setforth with respect to the following specific examples.

I Exar nple l I A 500 ml. reaction flask is charged with 200 g. .of

.o.chloronitrobenzene. A 133 g. quantity of electrolytic:

tacts the: o-chloronitrobenzene continues at a regular :ratethroughout-theentire addition and for ten minutes after the addition has been completed. The reaction mix- 'ture isthen-heated at 210 C.for an additional fifty .m'inutes'to complete the reaction. The mixture, after icooling' to about 130 C., is diluted with a mixture of rkerosene and alkylbenzeneshaving a boiling range be- -tween'13-5 C.--and 1'90 C. The catalyst residue is '-re'- moved by filtering and the filtrate cooled to precipitate'a substantial yield of o,o"-dinitrobiphenyl.

The identical procedurewas repeated except thatthe -electrolytic copper was not milled with stcaric acid prior to use. From the addition of the copper no reaction took place even 'though the temperature was increased to 240 C. After standing for thirty minutes, at which time 60 g. of the coppershad been added, the reactionabegan and soon became,stronglyqexothermic and difliculttocontrol. of the copper-wasjaddedat a rate necessary-lo keep the reaction under control. The product was then separated in the same manner and .aIlower ;yield of product .wasreco'vered- I I i vExa m ple 2 Using the procedure described inthe previous'example,

After the initial reaction had subsidedthe'sbalanc'e' 4 .groups, chlorine, bromine and iodine, at least one -01. said substituents being a halogen, in the presence of finely divided metallic copper and an acid having the structure R%OH wherein R is an aliphatic hydrocarbon radical, said acid having from 10 to 24 carbon atoms.

j 2. The method-of preparing compounds containing two identical aromatic nucleiin adjacent positions which'comprises heating at a temperature between 100 and400 I C. an aromatic hydrocarbon having a singlechlorine sub--- stituent in the presence of finelydivided metallic copper and from 0.1 to 10.0% (based on the metallic copper) of an acid having the structure Ri 3OH wherein R is an aliphatichydrocarbon; radical, .said acid having from.l0 to 24 carbon atoms.

'3; The method defined byclaim 1 wherein the ring; substituted aromatic hydrocarbon is o-chloronitrobenzene .and' wherein theacid is-oleic-acid. r

. 5. {Ihe methodtdefined by claim liwherein the-ringsubstituted aromatic hydrocarbon. is orchloronaphthalene and wherein theacid is oleic acid.

6. The method defined by claim 1 wherein the ring sub- -stituted aromatic hydrocarbon is chlorobenzene and Example 3 The procedure of the preceding example 'is repeated except that'bromobenzeneis used as-the principal reactant. A quickerand more efficient'reaction is obtained through the -use of copper powderimixed with a mixture offatty acid derived bythe saponification of coconut 'oil. The resultingproduct has the following'structure:

. Example 4 The procedures described in 1 to 3 above is repeated except that tX ChIOIOHEPhthaIGHQ was used as the principal reagents. with 5% stearic acid produces a compound identified as:

What is claimed is:

"1. The method of preparing bisymrnetrical aromatic compounds which compriscs'he'ating ring substituted aro- 'matic hydrocarbons wherein the 'said ring substituted groups are selected from the class consisting of alkyl radicals having'up to 3 carbon atoms, nitro radicals, oxo

A reaction utilizing bronze powder mixed wherein the acid is stearic acid.

7. The method defined by claim 1 wherein the ring substituted aromatic hydrocarbon is o-chloronitrobenzene and wherein-the acid is'stearic acid.

8. The method defined by claim 2 wherein the aromatic hydrocarbon containing a single chlorine substituent is chlorobenzene and wherein the acid is oleic acid.

9. The method defined by claim 2 wherein the aromatic hydrocarbon containing a single chlorine substituent is o-chloronitrobenzene and wherein-the acid is oleic acid.

10. The method defined by claim 2 wherein-the aromatic hydrocarbon containing a single chlorine substituent is o-chloronaphthalene and wherein the acid is oleic acid.

11. The method defined by claim 2 wherein the aromatic hydrocarbon containing a single chlorine sub References Cited in the file of this patent UNITED STATES PATENTS 11,92 ,055

Nieuwl'andet a1. Sept. 12, 1933 2,339,929 Houghton Jan-25, 1944 2,394,608 Hansley Feb. 12, 1946 Nowak et al.. J an. .29, 1952 OTHER REFERENCES Cohen: 7 .Organic Chemistry (London: Longmans, GIeen,&.Co., 1923), 4th edition, part I, pages 231-232.

' H'ansleyz Ind. :and Eng. Chern.,vol. 43, No; 8, August 1951, pp. 1759-1766 (pp. 1759 and51760 only relied on). Schmidt et a.l.: Organic Chemistry, Gurney and Jackson (London), 1950 (page 543relied on). 1 

1. THE METHOD OF PREPARING BISYMMETRICAL AROMATIC COMPOUNDS WHICH COMPRISES HEATING RING SUBSTITUTED AROMATIC HYDROCARBONS WHEREIN THE SAID RING SUBSTITUTED GROUPS ARE SELECTED FROM THE CLASS CONSISTING OF ALKYL RADICALS HAVING UP TO 3 CARBON ATOMS, NITRO RADICALS, OXO GROUPS, CHLORINE, BROMINE, AND IODINE, AT LEAST ONE OF SAID SUBSTITUENTS BEING A HALOGEN, IN THE PRESENCE OF FINELY DIVIDED METALLIC COPPER AND AN ACID HAVING THE STRUCTURE 